/Engine/Source/Runtime/AssetRegistry/Public/AssetRegistry/IAssetRegistry.h
Enumerate all PackageDatas in the AssetRegistry. The callback is called from within the AssetRegistry's lock, so it must not call arbitrary code that could call back into the AssetRegistry; doing so would deadlock.
void EnumerateAllPackages ( [TFunctionRef](API\Runtime\Core\GenericPlatform\TFunctionRef)< void([FName](API\Runtime\Core\UObject\FName) PackageName, const [FAssetPackageData](API\Runtime\CoreUObject\AssetRegistry\FAssetPackageData) &PackageData)> Callback ) const